Inflammatory skin disorders cover a broad category that includes many conditions ranging in severity, from mild itching to serious medical health complications. These disorders are common in people of all ages and races. They are characterized by irritation and inflammation of the skin. These diseases may sometimes be disfiguring and can cause great discomfort to the affected individual. A well-known example of inflammatory skin disorder is acne.
Acne is a multifactorial disease of the skin affecting more than 80% of young adults. This disease is localized to the pilosebaceous follicle and characterized by both inflammatory and non inflammatory lesions. Patients may present a mixture of non inflammatory comedons and inflammatory papules, pustules and nodules. One of the factors promoting the development of inflammatory acne is the bacterial colonization of the pilosebaceus duct by the anaerobic Proprionibacterium acnes (P. acnes) strain.
Indeed, P. acnes is able to induce in vitro production of proinflammatory molecules (interleukins IL-1α/ß, IL-8, IL-12, TNF-α, ß-defensins) by keratinocytes, sebocytes and monocytes but also in vivo in acne lesions. This production involves TLR2 receptor and activation of the NF-κB and MAPK signaling pathways as well as the NLRP3 inflammasome pathway. P. acnes also induces a massive production of reactive oxygen species (ROS) by keratinocytes, contributing to the initiation of the inflammatory reaction (Graham 2004; Grange 2009a; Grange 2009b; Kang 2005; Nagy 2005; Trivedi 2006; Qin 2014; Kistowska 2014, Jugeau 2005).
Currently, there are several anti-acne treatments such as retinoid (vitamin A derivatives), azelaic acid, salicylic acid, benzoil peroxide, topical and oral antibiotics etc.
These treatments act differently and have different effects. Generally, antibiotics kill bacteria, retinoid and azalaic acid prevent the development of microcomedones and have antimicrobial and anti-inflammatory properties etc.
Other chemical compounds target specific mechanisms linked to bacterial invasion.
P. acnes can adhere to human skin (Grice 2009) but also can cause deeper infections by travelling from its seeded area to the site of infection using non specific interactions and then irreversible adhesion process through specific binding (Gristina 1988). Moreover, previous study has shown the ability of P. acnes to bind to extracellular matrix proteins (ECM) as fibronectin (Yu 1997), as well as to human epithelial cell (Romero-Steiner 1990).
Among chemical drug having anti-adhesive agent, Papulex® is well known.
However, the above-cited treatments have many side effects. For example, antibiotic courses should be limited in the time and often, desensitization or loss of response is observed. Moreover, the use of chemical compounds induces several risks for patients, such as hypopigmentation in darker skinned patients or other side effects due to the treatment intolerance. Another drawback of using chemical compound for treating acne is their high cost (Dawson et, 2013).
For these reasons, other means, preferably biological means for treating and preventing acne should be developed allowing good efficiency of treatment without side effects and low production cost.